Filament support for tubular lamp

ABSTRACT

The invention relates to an electric filament lamp having a tubular envelope, in which a coiled coil filament is stretched. The filament is supported by a wire support a coiled part of which encloses a part of one turn of the filament, the inner diameter of said coiled part being maximum 1.5 times the outer diameter of the turn, and the length being minimum 1.5 times said outer diameter.

United States Patent Notelteirs et al.

[451 July 18, 1972 [54] FILAMENT SUPPORT FOR TUBULAR LAMP [72] Inventors: Victor Rosallie Notelteirs; Eduard Josef Philomena Jansen, both of Emmasingle,

21 App1.No.: 175,866

3,194,999 7/1965 Heinlein ..313/271 3,295,007 12/1966 Young ..313/274 X 3,390,299 6/1968 Van Sickler et a1. ..313/279 Primary Examiner-David Schonberg AnomeyFrank R. Trifari [57] ABSTRACT The invention relates to an electric filament lamp having a tu- [301 Foreign Application Priority Data bular envelope, in which a coiled coil filament is stretched. Sept. 3, 1970 Netherlands ..7013031 filament Suppmed by a supp a 1" which encloses a part of one turn of the filament, the inner [52] U.S.Cl. ..313/271,3l3/279, 313/315 iamete of sa d coiled part being maximum 1.5 times the [51] Int. Cl. ..H0lj 1/88 outer diameter of the turn, and the length being minimum 1.5 [58] Field oiSearch ..313/315, 316, 317, 271, 274, times said outer diameter.

313/279 3 Claim, 3 Drawing Figures [56] References Cited UNITED STATES PATENTS 3,168,670 2/1965 Levand ..313/274 I 1 1 I I I I r I 1 l 1 I I I IT'II] IIIIIIIIII 111 III 1 1 1 ['1' I PATENTEU JUL 1 8 I972 ggl u I I 3 a g I a 0 U 2 ll I INVENTORS VICTOR R. NOTELTEIRS EDUARD J.PH. JANSSEN AGENT The invention relates to an electric filament lamp comprising a tubular lamp envelope which is sealed at its ends by means of pinches and comprises a helically wound filament extending in the longitudinal direction of the lamp envelope, said filament being secured with its ends in the pinches of the envelope and being supported by a metal supporting wire in at least one place between the pinches of the envelope, the turns of said filament being each constituted by a number of helically extending wire windings, a part of the supporting wire cooperating with wire windings which occur in a part of only one turn of the filament. Such a filament lamp is known.

In the known filament lamps of this type, either the end of the supporting wire comprises a hook bent around a turn of the filament, or a part of the supporting wire is bent to form a loop which is closed around a turn of the filament. The drawback in these constructions is that the filament around the hook and the loop, respectively, can tilt in a plane perpendicular to the axis of the envelope so that the filament no longer extends centrally in the envelope.

It is the object of the invention to mitigate this drawback. For that purpose, an electric filament lamp according to the invention is characterized in that the supporting wire surrounds the wire windings occurring in apart of one turn of the filament with a coiled part the inner diameter of which is at most 1.5 times the outer diameter of the wire windings, and

the longitudinal dimension of which is minimum 1.5 times said outer diameter.

It is known per se to provide filament lamps with a supporting wire which comprises a coiled part, with which it is achieved that the filament extends coaxially in the envelope. A known filament comprises for that purpose a support manufactured from a piece of wire and the coiled part of which is slid around a few turns of the filament. A drawback in this 1 construction, however, is that the support locally screens the filament and as a result inhibits the light radiation.

When the direction of winding of the coiled part of the support is opposite'to that of the winding occurring in a turn of the filament, the enclosed part of the turn of thefilament will bear entirely inside "the coiled part of the support. An electric filament lamp according to the invention in which the direction of winding of the coiled part of the support is equal to that of the winding occurring in the turn of the filament is characterized in that the pitch of the coiled part is smaller than the pitch of the windings enclosed by said part. It is achieved by this measure that the enclosed part of the turn of the filament remains within the coiled part of the support.

In a filament lamp according to the invention, the part of the support remote from the filament may of course be secured to the envelope in various manners. This part may be secured, for example, in one of the pinches and the central part of the wire support may also be coiled and enclose a part of a turn of the filament, while the ends of the wire support are each secured in one of the pinches of the envelope.

The part of the wire support remote from the filament may 7 furthermore engage the inner wall of the envelope and be fixed in the axial direction by recesses provided locally in said inner wall.

In a favorable embodiment according to the invention, the end of the support remote from the filament is bent to form a barb which hooks behind the edge of an aperture in the wall of the envelope, into which aperture the sealed exhaust tube opens which projects laterally from the envelope, the inside diameter of said exhaust tube being larger than the diameter of the aperture. As a result of this it is achieved that during assembly the wire support with the filament secured thereto can be secured in the envelope in a simple manner.

In order that the invention may be readily carried into effect, it will now be described in greater detail, by way of example, with reference to the accompanying drawing, in which FIG. 1 shows a filament lamp according to the invention in which the part of the wire support remote from the filament is secured in an aperture in the wall of the envelope at the area of the tiEped-ofi art of the exhaust tube;

FIG. shows t e part of the wire support which encloses a part of a turn of the filament;

FIG. 3 shows the embodiment according to the invention in which the wire support is secured in the pinches of the envelope.

The filament lamp shown in FIG. 1 comprises an envelope 18 in which the filament 12 extends coaxially and the ends of which envelope are sealed by means of pinch seals 13. The filament 12 is secured in the pinches 13 by means of foils 14. The filament 12 is supported by a support 11 of which the end remote from the filament comprises a barbed hook 16 which is threaded through an aperture 8 in the wall of the envelope and hooks behind the edge 7 of the aperture 8. The sealed exhaust tube 17 has a larger inner diameter than the aperture 8.

FIG. 2 shows a turn 9 of the filament 12 which turn itself consists of a number of windings 15 of a wire which may be a coiled coil wire. The part a of the turn 9 is surrounded by the coiled part 10 of the wire support ll. The inner diameter b of said coiled part 10 is maximum 1.5 times the diameter of the winding 15 of the enclosed part of the turn 9. The length a of the coiled part 10 is minimum 1.5 times the diameter of the winding 15.

In the embodiment shown in FIG. 3, the filament 12 which extends coaxially in the envelope is supported in the center by the wire support 19 in the manner as was described with reference to FIG. 1. The parts 20 of the wire support 19 extend from the center of the envelope 18 in the direction of the pinches 13 in which the ends of the support 19 are secured by means of foils 21.

Because the coiled part 10 of the wire support 11 encloses a number of windings 15 of the turn 9, the filament 12 will extend coaxially in the envelope.

What is claimed is:

I. An electric filament lamp comprising a tubular envelope which is sealed at its ends by means of pinches and comprises a helically wound filament extending in the longitudinal direction of the envelope, said filament being secured with its ends in the pinches of the envelope and being supported by a metal supporting wire in at least one place between the pinches of the envelope, the turns of said fila-ment being each constituted by a number of helically extending wire windings, a part of the supporting wire cooperating with wire windings which occur in a part of only one turn of the filament, characterized in that the Supporting wire surrounds the wire windings occuring in a part of one turn of the filament with a coiled part the inner diameter of which is at most 1.5 times the outer diameter of the wire windings, and the longitudinal dimension of which is minimum 1.5 times said outer diameter.

2. An electric filament lamp as claimed in claim 1, in which the directions of winding of the coiled part of the support and of the windings of the filament enclosed by said part are the 1 same, characterized in that the pitch of the coiled part is 

1. An electric filament lamp comprising a tubular envelope which is sealed at its ends by means of pinches and comprises a helically wound filament extending in the longitudinal direction of the envelope, said filament being secured with its ends in the pinches of the envelope and being supported by a metal supporting wire in at least one place between the pinches of the envelope, the turns of said fila-ment being each constituted by a number of helically extending wire windings, a part of the supporting wire cooperating with wire windings which occur in a part of only one turn of the filament, characterized in that the supporting wire surrounds the wire windings occuring in a part of one turn of the filament with a coiled part the inner diameter of which is at most 1.5 times the outer diameteR of the wire windings, and the longitudinal dimension of which is minimum 1.5 times said outer diameter.
 2. An electric filament lamp as claimed in claim 1, in which the directions of winding of the coiled part of the support and of the windings of the filament enclosed by said part are the same, characterized in that the pitch of the coiled part is smaller than that of the windings enclosed by said part.
 3. An electric filament lamp as claimed in claim 1, characterized in that the end of the support remote from the filament is formed as a barb which hooks behind the edge of an aperture in the wall of the envelope, into which aperture the sealed exhaust tube opens which projects laterally from the envelope, the inner diameter of said exhaust tube being larger than the diameter of the aperture. 